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The University of Chicago

THE ZOOCECIDIA OF NORTHEASTERN
UNITED STATES AND EASTERN
CANADA

A DISSERTATION

SUBMITTED TO THE FACULTY
OF THE OGDEN GRADUATE SCHOOL OF SCIENCE
IN CANDIDACY FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY

DEPARTMENT OF BOTANY

BY
BERTRAM WHITTIER WELLS

Private Edition, Distributed By
THE UNIVERSITY OF CHICAGO LIBRARIES
CHICAGO, ILLINOIS

Reprinted from
Tue Botanica GAZETTE, Vol. LXV, No. 6
June, 1918

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The University of Chicago

THE ZOOCECIDIA OF NORTHEASTERN
UNITED STATES AND EASTERN
CANADA

A DISSERTATION
SUBMITTED TO THE FACULTY
OF THE OGDEN GRADUATE SCHOOL OF SCIENCE
IN CANDIDACY FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY

DEPARTMENT OF BOTANY

BY
BERTRAM WHITTIER WELLS

Private Edition, Distributed By
THE UNIVERSITY OF CHICAGO LIBRARIES
CHICAGO, ILLINOIS

Reprinted from
Tue BoraNnicaL GazETTE, Vol. LXV, No. 6
June, 1918

Slft
-~iVersity-

THE ZOOCECIDIA OF NORTHEASTERN UNITED STATES
AND EASTERN CANADA

CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 239
B. W. WELLS

This summary is based upon a completed descriptive account!
of the zoocecidia of the region studied, which is that phyto-
geographic region dealt with by Gray’s New Manual of Botany
(7th ed., r908). The only similar general statement preceding this
is that of Fett (4), who has presented some approximate figures
from an entomological standpoint pertaining to American insect
galls. The mite (Eriophyidae) galls were not included in his

discussion.
Historical

Three local studies of zoocecidia have been made which deserve
mention in a brief historical account. Cook (2) in 1904 published
the description of 66 galls from Indiana. JARrvis (7) in 1908
presented a catalogue of the insect galls of Ontario, comprising 221
species. STEBBINS (10) in ro1o described 205 species of galls
collected in the vicinity of Springfield, Massachusetts. <A post-
humous catalogue of 233 southern New England galls by THompson
(11) appeared in 1915, edited by Fretr. This also included a
summary of American Cynipidae galls, listing 350 species.

For the sake of comparison a short summary of the European
work will be given. HAIMHOFFEN (5) in 1858 presented 350 as the
number of zoocecidia for central Europe. SCHLECHTENDAL (9) in
1891 listed 1315 insect, mite, and nematode galls on the plants of
Germany. KIEFFER (8) in root published a synopsis of the
zoocecidia of Europe. There also appeared the same year a more
exhaustive study in Darspoux and Hovuarp’s (3) systematic

™ The work contains the description of 792 nematode, mite, and insect galls; half
of this number will be supplemented by illustrations. Keys to the galls on the various

plant genera have been made, the plant genus constituting the unit by which the galls
have been grouped.

535] [Botanical Gazette, vol. 65

536 BOTANICAL GAZETTE [JUNE

catalogue of the zoocecidia of Europe and the basin of the Mediter-
ranean, a work which in r908 (supplement 1913) was expanded by
Hovuarp (6) into the largest systematic cecidological work in exist-
ence. ‘This final general European work comprises the description
of 1950 zoocecidia.

Basis and plan of work

The data from which the following summary is drawn were
obtained during a period of 4 years, in which field studies in Con-
necticut, Ohio, and Kansas were supplemented by a thorough
canvass of the highly scattered cecidological literature.

It may be of interest to mention the simple’and, it is believed,
practical scheme which has been followed in the arrangement of the
792 types described. The plant genus was made the unit under
which the galls were grouped. This is in contrast to HOUARD’s
plan; he used the species, a plan which necessitated a vast amount
of repetition, since innumerable galls occur on more than one species
within the genus. It is a striking fact that very few galls are found
upon more than one genus. In the study of the galls of the north-
eastern United States, data concerning the plant species bearing
the gall have been included with the descriptive material. To
assist in locating the descriptions, keys were worked out for the
genera having more than 6 or 8 species. A brief bibliography
presenting the most important references was appended to each
description.

The plant genera in the work have been arranged alphabetically.
The galls under each genus have been aggregated according to the
classification of the cecidozoons. It is thus evident that artificial
classification has been pursued throughout. At the present time
any Classification of zoocecidia must be artificial. "The morphclog-
ical data available, particularly of an anatomical nature, are far
too meager to make possible anything approaching a natural
classification. :

Summary of numerical data

In the case of all of the following figures presented, it should be
understood that they are but approximations. So new is the field
of systematic zoocecidology in America, and so incomplete and

1918] W ELLS—ZOOCECIDIA 537

unsatisfactory are the data in innumerable specific instances, that
at the present time any generalizations of a numerical nature
cannot be accepted as expressing the exact condition.

A tabulated statement of the 792 galls known from the north-
eastern quarter of the United States and eastern Canada, according
to the cecidozoon orders and families, is as follows:

DISTRIBUTION BY ANIMAL FAMILIES

Nematoidea (Nematohelminthes) Gelechiidaes sae 4-5 ae ee B
/\iay UDO ANE. 5 Go choco hocencuae 2 lachistidaete eee eee 2
Acarida (Acarina) Sesiidlaern sy Mees: aches, soe ee I
iBnophyidaemes ae secon eee 87 MOrtmeldae’s 0.2.0. caes oe 2
Hemiptera (Insecta) Winclassitied: as caeet. = ee dee ie)
NPD ae mee. 1 bance scnnutl aye ess 70 ~=—- Diptera
esvilidaeperas cise acca tse 6 Hirypetidae-wy sees Pn aitoac ee Wl
JESSIOAG, ts Guat ones SEDC ae itomididaes s/s ada ates a 383
Coleoptera Hymenoptera
Ceranibyeldaiereen a meme ane: 2 @halcidaceee, 2.8 Saas ate eee 2
Biprestidaes en - sae ari eee: I Menthridinidaé ane. 5 ..ee eee a 13
Lepidoptera Gynipidae Srey ere ese 194
Mhineidaemeeiec ss acne ase fee ns I

As FEtT has pointed out, the family containing the most gall
makers is the Itonididae, embracing in our region 47 per cent of the
gall biota. The Cynipidae follow with 37 per cent. The other
families are represented by much smaller percentages, the Coleop-
tera being barely represented with 3 ill-defined galls.

The distribution of the galls (except nematode) by the plant
families on whose members they occur is as follows. The families
are arranged in the sequence given in GRAy’s Manual.

DISTRIBUTION BY PLANT FAMILIES

Rinacedemanneaaee ae 13 Aristolochiaceae...... DeROSACCHes Aaa ee 70
sliviphaceae see ease 1 Polygonaceae........ 2 becuminosdesos5. 08
Gramineae... 242, | 5) Chenopodiaceae: =... . 5 Euphorbiaceae....... 4
@yperaceae.. =. 4445 1 Nyctaginaceae....... z Anacardiaceae. ..:... 10
WUMEACEAC seins faa). m Portulacaceaé....2)..< EF, Aquitoliaceaewen . 22% I
Neiliaceaer was Sate ec 9 Ranunculaceae....... 7 (Gelastraceae.n)s -.. I
inidaceademanes ss4 c= t Magnoliaceae........ 2) NCEA CAC hyena tre 14
SHINCRCERIES acobeaoaee Go WZaumacedese s,s... oe 5 Balsaminaceae.......

Juglandaceae........ 64 Papaveraceae....:... bp Rhammaceaess... - 4° 2
Betulaceae...2....... Tow Crucilerdere. ce. aes Tir Witacedess: Aes sc0's: 20
Naga CeAe A anenatens se sees Ros woaxirapaceae. «a... 7 gy nila ceaien nn sor cet eye 7
Wirticacedesa.24-ee.- 37 Hamamelidaceae..... wee Mieilwalceae sass I

538 BOTANICAL GAZETTE [JUNE

DISTRIBUTION BY PLANT FAMILIES—Continued

iy EriGAGede ae ee Dy \OOCAKOEE woo aco ow oe < Te lealbiatadece nae 14
WAGE cos ceodene 2) Primulacede: | 0.42. -en ek olanaceacaaaree ener
(Cactacedee eter ww 18[URKCEO, cea cancers 2 Scrophulariaceae..... 2
liv tihnacea Cera ire tcrs mm (ONENESS oa cacncnedc 6) Biononiacedee--aaaaae
Onaeracedeann. aac: 1 ‘Apocynacede-....-.25 | © Rublacede saa 3
Nvaliaicedee ae eee 1 Asclepiadaceae....... 2. Capritoliaceac=neeeer 160
Wimbelilitertesss sees: 1’ Convolvulaceae...... 2 Compositae-.--2-.2: TAI
@omacereane saeco Tr Vertbenacese=-seraner 3

The striking fact brought out by this list is the extreme irregu-
larity of the distribution. Many of the larger families have few or
no galls, while on the other hand a few of the smaller families,
particularly the Fagaceae, possess many cecidia. Quercus alone
has 176 galls, of which 157 are cynipid types. FELT presents 277
as the approximate figure for the cynipid galls on the American
oaks. The Cynipidae-Quercus situation in Europe as well as in
America presents the most striking example of gall evolution within
a single genus of plants related to a comparatively few (9 or 10)
closely related genera of insects.

It is worthy of note that such large families as the Caryophyl-
laceae, Cruciferae, and Boraginaceae contain no gall-bearing species.
The Umbelliferae possess but a single gall. ‘The widely distributed
tree species Platanus occidentalis does not bear any zoocecidia.

The problem in distribution on the plants presented by the
preceding list is an exceedingly difficult one and probably cannot
be answered on the basis of the physiological information at present
available. This intimate and constant relation between specific
insects and specific plants forms one of the most significant phenom-
ena in the field of cecidology.

As far as data were obtainable, figures were worked out indi-
cating the distribution of the galls on the plant parts, with the
following result:

DISTRIBUTION ON PLANT PARTS

On leaf blade (of these 52 are “‘blis- Onsroots: 44-3. 25. ne ee ee 12
teregecallls)} \sv.csee cee oer eee A27e— aOnflowerseeeee ae Peet ys ee b,c DG

On petiole (most of these occur also From buds forming a rosette type... 47
Onbblade) fre cree ere oe 47. From buds forming a solid concentric

On stem (8 per cent of these occur CYPE. oa hclesinee oeee de POLAR 30

alsononstheuleat)e sc 45s sae eee 208

1918] W ELLS—ZOOCECIDIA 539

Slightly over half of the galls (53 per cent) occur on the leaf
blade. This fact is of course related to the relatively large amount
of embryonic leaf tissue exposed in the early stages of shoot develop-
ment. In the cases of the stem, root, and bud galls numerous
factors enter, but perhaps the most important is the factor of insect
equipment necessary to place the larval cecidozoon in contact with
the meristematic tissues.

Some figures pertaining to gall structure were obtained which
are of interest. A few words of explanation are necessary before
presenting the tabulation. Under the monothalamous galls were
included those types which, so far as could be determined, are
generally one-chambered, that is, the gall never is a structure
constantly characterized by the confluence of the walls of two or
more chambers as in the polythalamous condition. A few species
are intermediate and were classified in the direction in which it was
believed they leaned the more strongly. A number of galls, such
as the erineum (hypertrophied epidermal cells) types, do not fall
in either of the above categories and cannot be included in such a
classification.

In those cases in which sufficient data were available, an attempt
was made to study the galls on the basis of KUSTER’s division of
cecidia into kataplasmas and prosoplasmas. By ‘‘kataplasmas”’
KUSTER means those indefinite, indeterminate galls whose structure
is developed through hyperplasia of embryonic tissue, the end
product not becoming in its differentiation, orientation, and form
of tissues fundamentally different from the normal plant part.
“Prosoplasmas,’’ on the other hand, are highly definite and deter-
minate galls whose structure differs fundamentally from the normal
plant, the tissues in their form and orientation characters con-
stituting an aggregation of new qualities. These two groups
intergrade, but the intergrading forms are relatively few in number
and were classified according to what was believed to be the
predominating condition. In all cases where data were not suffi-
cient to pass judgment, the gall was omitted from the census.

Another set of figures presented is that based on KUsTER’s
classification of galls into organoid and histoid types. An
“organoid”’ gall is one in which an entire plant organ (leaf, stem,

540 BOTANICAL GAZETTE [JUNE

internode, ovulary, etc.) as a unit suffers modification without a
fundamental change in its morphology. The “‘histoid”’ galls are
those more numerous types in which an entire plant organ is not
involved, the gall being more or less definitely appendicular. This
group includes all of the prosoplasmas and part of the kataplasmas.

DATA BASED ON NUMBER OF CHAMBERS

Monothalamousjcallsisc escent oa eis tele Seer eee 408
Polythalamous galls... 2 j20.csige cat en eta) « coterie eee 134
iINon-chambered?gallisa. sae eer sericea dee el eet eee 67
Insufficientidatartojclassity = sees ee cee a Seca ree eee tet) cee 183

The excessively large number of monothalamous forms is a fact
related to the character of oviposition. If the eggs are habitually
deposited in an aggregate manner, a polythalamous gall is almost
certain to result, although there are striking exceptions to this.
The great majority of larvae, however, begin their gall-making
activity at sufficient distance apart to develop the common mono-
thalamous types of cecidia.

KATAPLASMAS AND PROSOPLASMAS

Karta plasmas s,s. 3.0! ¢.2r hickal vy hatuer uate ayers nase say eke niente ee eee ee 305
Prosoplasras. (ov. \ai. sete tastes Mie ears occa eal eat ee 322
Insutitcientidataito-classityan sciscme siacke sister eiaelenene irae eee TG

Viewed from an evolutionary standpoint, the kataplasmas
represent the lower levels and the prosoplasmas the higher. That
the latter have undergone a considerable expansion indicating
relatively rapid progress in recent geologic time is evidenced by the
relatively large number of prosoplasmas.

ORGANOID AND HISTOID GALLS

OpreaniOids sca c UMass sd ercpanehs ex tye teers eee ear ene Pt Sena ee 215
ERIStOIG So sa ave Seat atone f Gi Shean lee REE ee Pe aoe Oe Oe ee ee 405
Insuticient datastonclassilv:. sane el el tere ee ener ree 82

These figures have no special significance, perhaps, other than
the indication of differences in the range of the gall stimulus. In
the organoid types the stimulus is diffused over relatively large
areas, inciting all of the tissues of one organ to hypertrophy and
hyperplasia. In the histoid forms the stimulus only affects those
tissues in a restricted area about the cecidozoon, these tissues
responding in a definite and striking manner.

1918] WELLS—ZOOCECIDIA 541

In addition to the above two tables KUsrTer has, in his classifica-
tion of cecidia, furnished the basis for another table in his analysis
of the prosoplasmas. These he divides into four groups: the leaf
edge “roll” galls; the diverticulum or outpouching types; the
“walled” (umwallungen) forms, whose walls grow up about the
superficial larva; and the concentric (mark) cecidia whose larvae
inaugurate gall formation from a point within the tissue. In the
following list this classification was extended to include so far as
possible the kataplasmas also, since a great many of these latter
galls can properly be placed under some one of the preceding four
groups. The 58 “rosette”? and the 28 erineum types cannot be

included.
NUMBERS OF VARIOUS GALL TYPES

eatvedse roll’? types .2. ac se. 32 Concentric types
Diverticulum types Onileavess: sans. e aee 145
Leaf or leaflet fold along mid- Diss plea mn ee
unseen 2 ™9 — Galls unclassifiable in the above cate-
Fouch types proper...........+. 109 ZORICS 2,35 rota ata Meee eta, Ae 86
Walled (umwallungen) types....... 87 Unclassified through insufficient data 094

The factors entering into the production of these various kinds
of galls are many; a full discussion of them cannot be presented
here. Attention, however, should be called to the two main groups,
namely, those which are related to the plant and those related to
the cecidozoon. The diverticulum galls are, with few exceptions,
only known from the leaf, particularly the blade, since this organ
only is sufficiently free from stereome tissues to make possible the
characteristic pouching out on the side opposite the cecidozoon.
The walled and concentric types can occur on any part of the plant,
the latter constituting a much larger aggregation than any of the
other kinds. Oviposition within the plant tissue or a migration
inward on the part of the larva is necessary for the production of
the concentric type of gall. Even in these cases constituting the
highest galls, plant factors can exert a modifying influence. The
study of the relative importance of the two groups of factors
entering into cecidium morphogenesis in specific cases is one of the
most valuable and suggestive in the field of zoocecidology.

UNIVERSITY OF ARKANSAS
FAYETTEVILLE, ARK.

542 BOTANICAL GAZETTE. [JUNE

LITERATURE CITED

1. CONNOLD, E. T., British vegetable galls. New York. 1902.

2. Cook, M. T., The insect galls of Indiana. 29th Ann. Rept. Dept. Geol.
and Natural Hist. Indiana. pp. 801-867. 1904.

3. DarBoux, and Houarp, C., Catalog systematique des Zoocécidies de
Europe at du Bassin méditerranée. Paris. 1gotr.

4. Fett, E. P., American insect galls. Ottawa Nat. 30:37-39. 1916.

5. HatmHorFreEN, G. R., Beobachtungen tiber die Menge und das Vorkommen
der Pflanzengallen und ihre spezielle Verteilung auf die verschiedenen
Pflanzengattungen und Arten. Verhandl. Zool.-Bot. Gesell. 8:285. 1858.

6. Houarp, C., Les Zoocecidies des Plantes d’Europe et du Bassin de la
Meditteranee. 2 vols. Paris. 1909. Vol. 3, Paris. 1913.

7. Jarvis, T. D., A catalog of the gall insects of Ontario. 39th Ann. Rept.
Ent. Soc. Ont. 70-98. 1908.

8. KrEFFER, J. J., Synopsis des Zoocecidies d’Europe. Ann. Soc. Entom.
France. 70:233-384. 1901.

g. SCHLECHTENDAL, D. H. R. v., Gallbildungen (Zoocecidien) der deutschen
Gefasspflanzen. Zwickau. 1801.

10. STEBBINS, F. A., Insect galls of Springfield, Mass., and vicinity. Bull.
2. Springfield Mus. 1910.

11. THompson, M. T., An illustrated catalog of American insect galls. Edited
byjE. P: Fert: Nassau, NoY. 1075:

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